Bitmap.getPixel 始终返回黑色

Question

我正在创建一个应用程序，其中涉及获取屏幕部分的颜色。 为此，我使用 Bitmap.getPixel 方法来检索屏幕的指定像素，然后将其转换为 RGB 格式，以便以后更轻松地进行编码。问题是，当我使用 getPixel 方法时，无论屏幕上是什么，它总是返回相同的 RGB 值，R:0 G:0 B:0 或黑色，即使有一个灰色按钮覆盖整个屏幕！这是代码

package proof.of.concept;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.os.Bundle;
import android.util.Log;
import android.view.Display;
import android.view.View;
import android.widget.*;
public class ColorCheckerProofOfConcept extends Activity {
    private static final String TAG = "ColorChckerProofOfConcept:: ";  
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        final Button button = (Button) findViewById(R.id.button1);

     button.setOnClickListener(new View.OnClickListener() {
         public void onClick(View v) {
             Display display = getWindowManager().getDefaultDisplay();
                int width = display.getWidth();
                int height = display.getHeight();
                   Log.d(TAG, "Width and Height Retrieved As: " + width + ", " + height);
                Bitmap b = Bitmap.createBitmap(width, height, Bitmap.Config. RGB_565);
                String hexValue;

                 int test;
              test = b.getPixel(240, 350);

             hexValue = Integer.toHexString(test);
             Log.d(TAG, "pixel at 100, 200 succesfully retreived! with value of: " + test);
             Log.d(TAG, "and an Hex value of: " + hexValue);
             int blue = Color.blue(test);
             int red = Color.red(test);
             int green = Color.green(test);
//this is a modification

               Log.d(TAG, "RGB COLOR! R:" + red + " G:" + green + " B:" + blue);
         }
     });
   }
}

Answer 1

如果其他人正在寻找你应该做的事情......

//just add this is

    Canvas c = new Canvas(b);
    View view = ((ViewGroup)findViewById(android.R.id.content)).getChildAt(0);
    view.draw(c);

//right after you create your bitmap, that should print the screen onto the bitmap
//from there, you can use Bitmap.getPixel(X,Y)

Answer 2

您是从位图中提取的，而不是屏幕上的内容。您创建了一个黑色位图，其大小与屏幕大小相同，但与屏幕大小无关。您的代码适用于从该位图中提取。您是否正在尝试创建屏幕位图？